The present invention relates to a method for manufacturing a semiconductor device, and more particularly, to a method for manufacturing a semiconductor device that can easily form a fine pattern.
As semiconductor devices become highly integrated, the critical dimensions and distances of patterns have been miniaturized. Generally, in the manufacture of a semiconductor, exposure and etching processes are performed to form a desired pattern. Specifically, forming a photoresist pattern over a pattern forming film using a lithography process forms the pattern. The pattern forming film is subsequently etched using the photoresist pattern as an etching mask.
Accordingly, the lithography technology is an important element to form the fine pattern. Conventional lithography is performed by exposing a pattern of a reticle on the photoresist using KrF or ArF and developing the pattern of a reticle to form the photoresist pattern.
However, in a highly integrated semiconductor device, a step height is raised and the pattern formation method using a photoresist with ArF for exposure poses a limitation. The limitation results from an optical effect due to a short wavelength and a chemical effect induced by using a chemically amplified photoresist.
To overcome this limitation, a method of forming a nitride layer series material or amorphous carbon over a target layer to be etched and used as an etching mask has been utilized. Hard material other than the photoresist as previously mentioned used as an etching mask is referred to as a hard mask.
Hereafter, a method for forming a pattern using a hard mask according to the conventional art will be briefly described.
A hard mask layer made of a nitride layer series material or amorphous carbon is formed over a pattern forming film, i.e. over the target layer to be etched. An anti-reflective layer made of a material such as SiON, is formed over the hard mask layer. A photoresist is then coated over the anti reflective layer and the photoresist coating is sequentially exposed and developed forming a photoresist pattern.
The anti-reflective layer and the hard mask layer are etched using the photoresist pattern as an etching mask to form a hard mask. The remaining photoresist pattern is then removed. The remaining SiON anti-reflective layer and photoresist pattern are removed together. The removal of the photoresist pattern may be omitted. The target layer is etched using the hard mask as an etching mask to form a desired pattern.
However, the integration of semiconductor devices is progressing much faster than the development of exposure apparatuses. As a result, it is impossible to form the fine pattern required for a semiconductor device of 40 nm technology or less with current exposure apparatuses. Further, a pattern forming method using a hard mask cannot attain a fine size hard mask in a semiconductor device having a feature size less than 40 nm and causes an additional problem, i.e., pattern collapse.
Therefore, there is an urgent need for a method of forming the fine pattern required by a semiconductor device of 40 nm technology or less utilizing an existing exposure apparatus to eliminate the need for further investment in a new exposure apparatus.